JP2635168B2 - Metallic pigment for powder coating and enamel product using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metallic pigment for powder coating having a noble metal-colored luster and an enamel product using the same.

(Prior Art) Metallic pigments having a color and luster like a noble metal by coating a thin film of metal such as titanium oxide on the surface of mica powder have been known as disclosed in JP-B-62-3873. Are known. However, when this metallic pigment was mixed with a frit and used in an enamel product, the metallic pigment was eroded when fired at 800 to 860 ° C., and the color tone became uneven, so that a uniform and beautiful enamel product could not be obtained. For this reason, attempts have been made to solve this problem by suppressing the alkali component in the frit.However, if the alkali component is suppressed, it becomes difficult to burn at a low temperature, and workability deteriorates. Could not get to.

In addition, this type of metallic pigment can produce a clearer color tone when dry-glazed by the powder coating method than when wet-glazed, but conventional metallic pigments do not have sufficient fluidity and adhesion, and are not uniform. Powder coating has not been easy.

(Problems to be Solved by the Invention) The present invention has been completed in order to solve the above-mentioned conventional problems, and a first object of the present invention is to prevent erosion at the time of sintering, and to further reduce the powder. An object of the present invention is to provide a metallic pigment which can be glazed with high adhesion efficiency by a coating method. A second object is to provide a metallic enamel product manufactured by a dry glaze method using the metallic pigment.

(Means for Solving the Problems) A first invention made to solve the above problems is as follows.
On the surface of powdered mica, a coating layer of titanium oxide or iron oxide, a coating layer of alumina or zirconia, a resin coating layer of a silane compound, and a coating layer of an organopolysiloxane are sequentially formed. The subject matter is a metallic pigment for powder coating.

According to the second invention, a coating layer of titanium oxide or iron oxide, a coating layer of alumina or zirconia, a resin coating layer of a silane compound, and a coating layer of an organopolysiloxane are sequentially formed on the surface of powdered mica. The metallic pigment, on the outer surface of the enamel frit powder, a resin coating layer of a silane compound,
The gist of the present invention is to provide an enameled product characterized in that an organopolysiloxane coating layer is formed and glazed on an iron plate together with an enameled frit powder.

 Hereinafter, the configurations of these inventions will be described in more detail.

(Metallic pigment)

The metallic pigment of the present invention is obtained by further adding three coating layers to the structure of an ordinary mica pigment in which a coating layer of titanium oxide or iron oxide is formed on the surface of powdered mica. First, the alumina or zirconia coating layer is for preventing the mica pigment from being eroded during firing, and is indispensable for obtaining an enamel product having a uniform and vivid color tone.

In order to obtain such a coating layer, for example, a conventional mica powder having a layer of titanium oxide or iron oxide is dispersed in water, an aqueous solution of aluminum sulfate is added as an acid having a pH of 3 to 4 and the solution is kept at 60 ° C. for 1 hour. After that, it may be filtered and dried. Further, triethoxyaluminum Al (OC ₂ H ₅ ) ₃ , tetraethylzirconer Zr (OC ₂ H ₅ ) ₄ or the like may be hydrolyzed and coated by a known sol-gel method. Thickness of coating layer of alumina or zirconia is several μm
Is sufficient, and if the thickness is too large, color development may be hindered. The reason why the material is alumina or zirconia is that they have a function of effectively protecting the mica pigment from alkali components in the frit.

The metallic pigment of the present invention further has on its outer surface a resin coating layer of a silane compound and a coating layer of an organopolysiloxane. A metallic pigment having such a coating layer has a large electric resistivity and excellent adhesion, and also has excellent fluidity.

In the present invention, the resin coating layer of the silane compound formed on the outer surface of the metallic pigment has a general formula of R-Si (OR ₁ ) _4-n (where R is an alkyl group, a vinyl group or a combination thereof, ₁ is a methyl group, an ethyl group, n is 1 or 2) silane, or a silane coupling agent formed by reacting with a metallic pigment,
Preferably, 0.1 to 2.0% by weight of silane, based on the metallic pigment, and a silane coupling agent are applied. R and R ₁ in the above general formula preferably have 6 or less carbon atoms, and if they have more carbon atoms, decomposition of carbon in the silane compound in the firing step (about 800 ° C.) after powder coating. Dispersion is not performed quickly, and defects such as foaming are likely to occur.

The organopolysiloxane film adhered to the outer surface of the resin coating layer has a general formula (Wherein R is an alkyl group or hydrogen, R ₁ is an alkyl group, n
Is an integer in the range of 5 to 300), after treating the surface of the metallic pigment with a silicone oil represented by
It is fixed by heat-curing treatment at 200 ° C. for 20 to 120 minutes, and preferably 0.1 to 2.0% by weight of organopolysiloxane is applied to the metallic pigment. It is the same as in the case of the above-mentioned silane that R in the above general formula preferably has 6 or less carbon atoms. When the polymerization degree n is 5 or less, the organopolysiloxane has low viscosity and is volatile, so that it is difficult to use it.
When the molecular weight is 300 or more, the polymerization proceeds excessively, and the carbon content in the organopolysiloxane is not rapidly decomposed and scattered in the firing step, so that defects such as foaming are easily caused. Accordingly, the range of the polymerization degree n is suitably from 5 to 300, and particularly those having a value of n of from 30 to 250 are easy to handle, and are most preferable because they do not cause defects such as foaming in the firing step.

In the metallic pigment of the present invention described above,
A siloxane bond (-Si-O-Si-) is formed on the surface by a dehydration reaction with silane and a dehydration condensation reaction between silanol groups (-Si-OH) in adjacent silane molecules to form a hydrophobic resin coating layer. Is formed on the resin coating layer, and the hydrophobic organopolysiloxane is very well blended and uniformly coated, and a strong organopolysiloxane film is fixed. As described above, since the uniform coating of organopolysiloxane having excellent electrical insulation is formed on the surface of the metallic pigment of the present invention, the electrical resistivity is significantly improved as compared with the case where only the silane compound is used. In addition, the adhesive force when powder coating is performed is excellent. In addition, those treated with only the organopolysiloxane have poor compatibility between the hydrophilic surface and the hydrophobic organopolysiloxane, so that a uniform coating cannot be formed on the surface of the pigment, resulting in partial hydrophilic portions and poor fluidity. And the adhesion efficiency becomes worse,
As in the present invention, an organopolysiloxane coating film formed on the outer surface of a resin coating layer of a silane compound has a large electric resistivity and excellent fluidity.

As described above, the mica pigment of the present invention prevents erosion during firing by a coating layer of alumina or zirconia, and improves fluidity and adhesion during powder coating by a coating layer of a silane compound and a polysiloxane. It is a thing.

[Enamel products]

The enamel product of the second invention is obtained by glazing the above-mentioned metallic pigment of the first invention and the enamel frit powder on an iron plate by a powder coating method. And a coating layer of an organopolysiloxane. Since the method of forming each of these layers and the function and effect thereof are the same as those of the metallic pigment, the description thereof will not be repeated.

In the enamel product of the present invention, the mica pigment and the enamel frit powder are dry-glazed on an iron plate to form a metallic glaze layer. As the glazing method, a first method of mixing the two and powder coating, and a second method of first coating the enamel frit powder with powder and then coating the mica pigment with powder.
And a third method in which powder coating is performed in the order of mica pigment and enamel frit powder.

In the case of the first method, the mica pigment is mixed at a ratio of 1 to 15 parts by weight with respect to 100 parts by weight of the enamel frit powder. If the mica pigment is less than 1 part by weight, a metallic feeling cannot be obtained, and if it exceeds 15 parts by weight, the normal firing temperature of 800 to 860
It cannot be fired at ℃. In addition, 1 mica pigment
Up to 7 parts by weight provides a good glossy and deep metallic feeling, and 7 to 15 parts by weight provides a semi-matte or matte and brilliant color tone.

In the case of the second method, the thickness of the mica pigment layer is 5-20.
μ. If it is less than 5 μm, a metallic feeling cannot be obtained. Conversely, if it exceeds 20 μm, the strength of the metallic glaze layer is reduced, and the metallic glaze layer comes off when rubbed by hand.

Also in the case of the third method, the thickness of the mica pigment layer is 5 to 20 μm.
And If it is less than 5μ, the metallic feeling cannot be obtained,
If it exceeds 20 μm, the lower glaze layer and the metallic glaze layer are apt to peel off at the upper part of the mica pigment layer.

Since the enamel product of the present invention thus configured contains a mica pigment whose outer surface is coated with alumina or zirconia, it does not corrode even when fired at 800 to 860 ° C. and has a uniform color tone. A vivid metallic feeling can be obtained. Further, in the present invention, since the outer surface is coated with a metallic pigment and an enamel frit powder having excellent electrical resistivity and flowability coated with a silane compound and an organopolysiloxane, the adhesion efficiency to the lower glaze layer is improved. A metallic enameled product can be easily obtained by a dry glaze method using powder coating. In addition, the metallic enamel product manufactured by the dry glaze method can obtain a color tone which is much better than that obtained by the conventional wet glaze method.

(Example) Example _{1 SiO 2 59%, B 2} O 3 8%, TiO 2 5%, Na 2 O 16%, K 2 O 8
%, Li ₂ O 1%, F 3%, 1 kg of transparent frit is ground in a pot mill to a particle size of 8 to 10 g / 50 g / 350 mesh on with a ball mill, and the obtained enamel frit powder is stirred with a mixer. Then, 5 g of methyltrimethoxysilane was added dropwise. After stirring for 30 minutes, dimethyl silicone oil (n =
100) 2 g was added dropwise and mixed for another 30 minutes, and then the enamel frit powder was heated in a dryer (150 ° C.) for 60 minutes to obtain an enamel frit powder for powder coating. On the other hand, a mica pigment having a 3 μm-thick alumina coating layer formed on the surface of mica powder having a titanium oxide coating layer on the surface is prepared, and 5 g of methyltrimethoxysilane is added dropwise with stirring with a mixer for 30 minutes. The mixture was mixed, and 2 g of dimethyl silicone oil (n = 100) was added dropwise, and the mixture was further mixed for 30 minutes. Then, the pigment is dried (15
(0 ° C.) for 60 minutes to obtain the mica pigment of the first invention. Then, 50 g of this mica pigment was added to 1 kg of the above-mentioned enamel frit powder, and mixed with a mixer for 10 minutes.

Next, a 100 × 100 × 1.6 mm ^t enameled steel sheet is pre-treated by a conventional method, coated with a lower glaze, dried, and then placed in an electric furnace at 820 ° C. × 3.
A test piece was prepared by baking for minutes. On this test piece, a mixed powder of enamel frit powder and mica pigment was powder-coated using a GEMA710 type electrostatic coating apparatus. The applied voltage was 50 KV, and the thickness of the metallic glaze layer after baking at 800 ° C. for 3 minutes was 100 μm. The resulting product has a metallic appearance with a deep gloss and excellent gloss.

In addition, 9 kg of mica pigment is added to 1 kg of enamel frit powder.
When 0 g was added, the resulting product had a semi-matte tone, and when 120 g of the mica pigment was further added, a mat-like metallic product was obtained.

Example 2 An enamel frit powder similar to that of Example 1 was powder-coated on a test piece at an applied voltage of 50 KV in the same manner as in Example 1, glazed to a film thickness of about 100 μm, and applied on its upper surface at an applied voltage of 70 KV. The mica pigment of Example 1 has a film thickness of 10
Powder coating was performed to about μm. Then 800 ℃ ×
After baking for 3 minutes, a semi-matte enameled product with a beautiful appearance was obtained. When the thickness of the mica pigment layer exceeded 20 μm, the mica pigment on the surface was easily peeled off.

Example 3 Contrary to Example 2, a mica pigment was powder-coated on a test piece, and then an enamel frit powder was powder-coated. The product obtained in this way had a metallic appearance with a deep gloss. When the thickness of the mica pigment layer exceeded 20 μm, it was easy to peel off at the interface between the lower glaze layer and the metallic glaze layer as the upper glaze layer.

(Effect of the Invention) As described above, according to the first invention, 800 to 8
A metallic pigment which does not corrode even when baked at 60 ° C., has excellent adhesiveness and fluidity, and is easily powder-coated can be obtained. According to the second aspect of the present invention, it is possible to obtain a dry enameled enamel product having excellent color tone and uniformity by using this metallic pigment. Therefore, the present invention greatly contributes to the development of industry as a metallic pigment for powder coating which solves the conventional problems and an enameled product using the same.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-92359 (JP, A) JP-A-63-133025 (JP, A) JP-A-64-33031 (JP, A) JP-A-64-33031 36775 (JP, A) JP-A 1-158077 (JP, A)

Claims (2)

(57) [Claims] 1. A coating layer of titanium oxide or iron oxide, a coating layer of alumina or zirconia, a resin coating layer of a silane compound, and a coating layer of an organopolysiloxane are sequentially formed on the surface of powdered mica. A metallic pigment for powder coating, characterized by the following. 2. A metallic material comprising a mica powder, a titanium oxide or iron oxide coating layer, an alumina or zirconia coating layer, a silane compound resin coating layer, and an organopolysiloxane coating layer sequentially formed on the surface of the powder mica. An enamel product, wherein a pigment is glazed on an iron plate together with an enamel frit powder having a resin coating layer of a silane compound and a coating layer of an organopolysiloxane formed on the outer surface of the enamel frit powder.